Michael E. Pfrender - US grants

0212487
Pfrender

Contemporary natural populations are faced with a challenging suite of changing environmental conditions. The ability of populations to adapt to new conditions depends, in large part, on the patterns of genetic variation underlying adaptive characters. A well-developed theoretical framework exists for analyzing the rate and trajectory of adaptation. However, there is a lack of sufficient empirical data to extend this framework to make predictions about the potential for populations to adapt to changing conditions. This research will make direct comparisons of freshwater invertebrate populations before and after a rapid change in the environment, focusing on a suite of alpine lakes in the Sierra Nevada Mountains of California that have known histories of fish introductions. Estimates of the rate and trajectory of adaptation will be obtained by hatching eggs from lake-bottom sediments prior to the introduction of fish and comparing the historical and contemporary populations.

Given the current level of anthropogenic influences on the environment, understanding the limits to the process of adaptation in natural populations is critically important. The results of this research will provide important insights into the ecological and genetic processes in natural populations and will be directly applicable to the conservation and management of natural resources and biodiversity, particularly when these are challenged by phenomena such as climate change and invasive species. Sediment cores obtained in these studies will document historical changes in abiotic and biotic lake structure and will be a valuable resource for researchers across a wide range of disciplines. Research and education will be integrated through the training of graduate and undergraduate students. The results of this work will be disseminated widely through peer-reviewed journals and direct contact with federal agencies.

[unreadable] DESCRIPTION (provided by applicant): Understanding the interaction of the genome and the environment is an important public health consideration since many human disorders with complex genetic architectures are highly influenced by interactions between genetic and environmental factors. A critical need is the development of study systems with well advanced genomic infrastructures that also have tractable and well understood ecological contexts. Daphnia is a logical candidate study system for further development to fill this gap. Daphnia has long been considered one of the premiere systems for ecological study and recent advances have lead to a rapidly expanding genomic infrastructure including a complete genome sequence and gene expression arrays. To advance Daphnia as a model for understanding the interplay between genome structure/function and environmental factors in the development of complex phenotypes, we propose to establish mapped QTL panels and a SNP database as a shared resource for the research community. Since unique genotypes of Daphnia can be maintained indefinitely through clonal reproduction, mapped QTL panels will provide a sustainable resource enabling multiple researchers to capitalize on the rapidly advancing genomic infrastructure of Daphnia. Increasingly, research on complex phenotypes utilizes a combination of QTL analysis and microarray expression profiles (eQTLs). The application of these two methods, referred to as genetical genomics, in a model system in which environmental conditions can be accurately and systematically manipulated will significantly advance our understanding of the relationship between the phenotype and the underlying genotypic and environmental effects. Specifically we will: (1) Establish QTL mapping panels of F2 recombinant lines from relevant strains of Daphnia. (2) Develop a SNP database to facilitate fine-scale mapping. (3) Generate a high-density genetic map for each panel using a combination of microsatellite loci and SNP markers. (4) Establish the bioinformatics infrastructure to integrate genetic and phenotypic data from these panels with existing genomic data. (5) Maintain and distribute live cultures of the recombinant lines to enable QTL studies relevant to a wide range of research areas and provide bioinformatics support for this resource. [unreadable] [unreadable] [unreadable]

Newts defend themselves from predators such as snakes by secreting a potent nerve poison, tetrodotoxin (TTX), but some populations and species of garter snakes have evolved resistance to TTX. The molecular mechanism for this resistance is known, as is one of the genes involved, providing an excellent opportunity to investigate the evolutionary genetics of a trait that has a clear adaptive value. The studies will include a survey of the genetic differences underlying the variation in resistance to TTX in different populations and species of garter snakes and a molecular genetic evaluation of the role of natural selection in the evolution of resistance. Several factors could underlie the presence of resistance in multiple populations. These are multiple episodes of independent evolution, spread across populations, or shared ancestry; these alternatives will be tested with molecular genetic analyses. The research will result in disentangling the role of novel mutations, recombination, and gene flow in explaining the geographic patterns of phenotypic diversity.

This project will help to support graduate and undergraduate education in behavioral and molecular genetics. The PIs will promote the participation of minorities and women in science careers through the Utash State University NSF ADVANCE program, the USU Multicultural Research Fellowship Program, and the Mountain Lake Biological Station REU program. The snake-newt system will continue to be developed as a model to illustrate the evolutionary process to the general public through outreach education (similar to the recent PBS-TV material and articles in popular media) and exhibits in museums.